1. Field of the Invention
This invention relates to a battery case for an electrically operated device and more particularly to a battery case having a light bulb mounted thereon and constructed to receive a consumed cassette film pack of a photographic camera which provides the electrical energy to illuminate the light bulb mounted on the battery case thereby employable as a flashlight.
2. Description of the Prior Art
U.S. Pat. Nos. 3,563,805; 3,617,387; 3,734,780; disclose planar energy cells or batteries intended for use as an individual power source for portable electrically operated devices. The multicelled planar batteries are employed commercially to operate photographic cameras such as the camera sold by Polaroid Corporation, Cambridge, Mass. under the trademark "SX-70".
When used in a photographic camera, the multicelled planar battery is housed within a cassette or film pack. The cassette houses both the planar battery and a number of film units for selective sequential exposure. The multicelled planar battery provides the electrical energy necessary to operate the camera's exposure control, film transport, and photoflash systems.
U.S. Pat. No. 4,181,778 dicloses a multicelled planar battery that is housed within a film pack cassette. The battery is a "wafer-thin" battery constructed with individual battery cells in superimposed or stacked configuration and in electrical series relationship. The number of stacked cells is determined by the power output of each cell and the power requirements of the device to be energized by the battery.
The battery ordinarily comprises a LeClanche electrochemical system that includes a zinc negative anode system and a manganese dioxide positive or cathode system as disclosed in U.S. Pat. No. 3,770,504. The multicelled battery is positioned within the cassette so that the electrical leads of the battery are exposed at the terminal ports of the cassette and engage the electrical leads of the camera. A spring platform is positioned between the planar battery and the stack of individual film units. Generally ten film units are provided in each film pack. Each film unit is individually and sequentially ejected from a passage through one end of the cassette.
One of the primary features of the cassette film pack is the electrical power capacity of each of the battery cells comprising the multicelled unit. Each cell is operable to produce about 0.10 to 0.15 ampres per square inch of surface area while yielding 1.5 volts. With this arrangement, the battery has a capacity for a film supply-power source having a considerable storage life necessitated by the fact that the film pack may be maintained in storage for sometime before it is used.
It is the customary practice to discard the above described cassette film pack after the individual film units have been exposed by operation of the camera being powered by the multicelled planar battery. Because the battery has a considerable storage life, the power capacity of the multicelled planar battery is not consumed in operating the camera to expose the individual film units and power the other camera instrumentalities. Therefore, the multicelled planar battery has considerable reserve power remaining after the film units have been exposed. This reserve power is otherwise wasted when the multicelled planar battery is discarded with the expended film pack. Therefore, there is need to provide an apparatus that utilizes the reserve power of an expended photographic film pack in the practice of energy conservation.